<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="box">
        <label for=""> <input type="checkbox" >两周内自动登陆</label>
        <div id="sb">为了您的信息安全，请不要在网吧或公用电脑上使用此功能！</div>
    </div>
</body>
<script>
    let box = document.querySelector("#box")
    let sb = document.querySelector("#sb")
    box.onmouseover = function(){
        sb.style.display = "block"
    }
    box.onmouseout = function(){
        sb.style.display = "none"
    }
</script>
<style>
    body{
        width: 100%;
        display: flex;
        justify-content: center;
    }
    #sb{
        padding:5px;
        margin-top:5px;
        background:#ffefa4;
        border:1px solid #f90;
        display:none;
    }
</style>
</html>